(1) Field of the Invention
The present invention is directed to the field of manufacturing display devices such as liquid crystal display devices, EL display devices and the like. The invention relates to a production method for an adhesive lamination for adhering films (such as TAB films), at least having electrodes, to elongated circuit boards, a production method for a circuit board using the adhesive lamination as well as relating to a display device using the circuit board and a production method for the display device.
(2) Description of the Prior Art
Conventional liquid crystal display (LCD) devices are formed of an LCD panel having a multiple number of TAB films electrically connected thereto and some elongated circuit boards electrically connected to these multiple number of TAB films.
The method of electrically connecting these multiple number of TAB films to the elongated circuit board is briefly described below.
First, in order to position a multiple number of TAB films to the elongated circuit board at predetermined positions, a strip of adhesive tape which is composed of a separation sheet and an adhesive layer and is wound up as in a reel, is cut into the length which extends across a plurality of TAB films provided on one side of the LCD panel, and the thus cut adhesive tape is applied directly on one elongated circuit board in parallel therewith.
Then, the separation sheet is removed to expose the adhesive layer, and the plural TAB films jointed to the LCD panel are positioned relative to the circuit board so that the electrode terminals on both sides correspond to each other. In this arrangement, the TAB films are laid over the circuit board and pressed on the area with the adhesive layer against the circuit board so that the TAB films are adhered and fixed onto the circuit board.
Thereafter, the electrode terminals of TAB films are electrically joined with solder to those of the circuit board.
Recently, a proposal has been made in which the frame of the display window for the LCD device is made narrower to improve the effective area of the display. However, in the above conventional art, it was impossible to make the width of the circuit board narrower.
Illustratively, in the proposed configuration, it is necessary to provide a number of electronic parts such as capacitors, buffer ICs, operational amplifiers, densely and compactly on the circuit board. It is also necessary to provide holes for screws which fix the circuit board to the plastic chassis, or to form cutouts for the fixture of the LCD panel to the plastic chassis by engaging bezel claws. However, the above prior art configuration suffered from problems in that the adhesive layer tended to rise up from the surface of the board near the electronic parts or the adhesive layer blocked the holes for screws, and cutouts. Therefore, it became impossible to apply the tape with an adhesive layer, onto the circuit board without modification.
In order to solve the problems, there is a method of providing a TAB film onto the circuit board without making a plurality of adhesive patches corresponding to the electrode terminal portions of the TAB films.
However, since in this method, plural adhesive patches were sporadically distributed without corresponding to the positions of electrode terminal portions of the TAB films, when the electrode terminals of the TAB films were soldered to those of the circuit board, the film terminals near areas with no adhesive layer tended to rise up so that soldering failure was likely to occur.
Even in the case where the soldering was performed well, since the uniting strength was weak in the areas where no adhesive layer was provided, TAB films tended to separate or the soldering tended to become disconnected due to tensile stress which could occur during assembly of the LCD device.
Further, since the adhesive layer was formed patch by patch on the circuit board, the efficiency of the assembly was low, thus raising the cost.
The present invention has been achieved in view of the above problems, and it is therefore an object of the present invention to provide an adhesive lamination which is composed of a number of patches of an adhesive layer and is applied across a plurality of circuit boards by making the patches corresponding to predetermined positions on the circuit boards, thus making it possible to reduce the cost and improving the efficiency of the operation of applying the adhesive layer to the circuit board, as well as improving the reliability of electrical connection between TAB films and the circuit boards.
It is another object of the invention to provide a production method for a circuit board which by using the adhesive lamination, makes it possible to produce a circuit board with an adhesive layer attached thereon, at high work efficiency at low cost.
It is a further object of the invention to provide a liquid crystal display device and a production method therefore wherein it is possible to make the frame of the display window narrower and compact and improve the reliability of electrical connection by using the above circuit board with an adhesive layer attached thereon.
It is a still another object of the invention to provide a production method for a liquid crystal display device which is excellent in the work efficiency and enables the production of inexpensive liquid crystal display devices by forming an anisotropically conductive adhesive layer of a circuit board chain.
In order to attain the above object, the present invention includes the following configurations and devices.
In accordance with the first aspect of the invention, an adhesive lamination comprises patches of an adhesive layer which correspond to predetermined positions on a plurality of circuit boards, and is configured so that the adhesive layer is applied across the plurality of circuit boards.
In accordance with the second aspect of the invention, an adhesive lamination having the first feature, further comprises: a first separation sheet off an elongated rectangle; and a second separation sheet, and is characterized in that the patches of an adhesive layer are of an elongated rectangle, formed between the first and second separation sheets and are arranged on the first separation sheet so that the length of thee patch of the adhesive layer is approximately parallel to the short side of the first separation sheet.
In accordance with the third aspect of the invention, an adhesive lamination having the second feature is characterized in that the adhering strength between the first separation sheet and the adhesive layer is greater than that between the second separation sheet and the adhesive layer.
In accordance with the fourth aspect of the invention, an adhesive lamination having the second or third feature is characterized in that a plurality of the first separation sheets are provided on the second separation sheet, and the first separation sheets are repeatedly laid out or arranged facing one another.
In accordance with the fifth aspect of the invention, an adhesive lamination having the second or third feature is characterized in that a plurality of the first separation sheets are provided on the second separation sheet, and each of the first separation sheets is shaped in a comb-like form so that a pair of the first separation sheets are laid out mated to one another.
In accordance with the sixth aspect of the invention, an adhesive lamination having the second or third feature is characterized in that the patches of the adhesive layer formed on the first separation sheet are arranged at intervals corresponding to that of the circuit boards arranged in the circuit board chain which is formed of a series of circuit boards.
In accordance with the seventh aspect of the invention, an adhesive lamination having the second or third feature is characterized in that the adhesive layer is formed so that each film, at least having electrodes, corresponds to one patch of the adhesive layer.
In accordance with the eighth aspect of the invention, an adhesive lamination having the second or third feature is characterized in that the length of the patch of the adhesive layer is approximately equal to the length of the electrode terminal portion formed on the film, at least having electrodes.
In accordance with the ninth aspect of the invention, an adhesive lamination having the seventh feature is characterized in that the length of the patch of the adhesive layer is approximately equal to the length of the electrode terminal portion formed on the film, at least having electrodes.
In accordance with the tenth aspect of the invention, a production method for a circuit board having an adhesive layer, comprises the steps of:
forming patches of the adhesive layer which correspond to predetermined positions across a plurality of the circuit boards arranged in a circuit board chain which is formed of a series of the circuit boards; and breaking the circuit board chain with the adhesive layer attached thereon, into separated pieces of circuit boards.
In accordance with the eleventh aspect of the invention, an LCD device comprises: a plurality of films which, at least have electrodes and are connected with an LCD panel; and a circuit board, the films being adhered and fixed to the circuit board with an adhesive layer, and the electrode terminals of the film, at least having electrodes, are electrically connected to the electrode terminals of the circuit board, and is characterized in that a plurality of patches of the adhesive layer are formed corresponding to predetermined positions across a series of the circuit boards.
In accordance with the twelfth aspect of the invention, a production method for an LCD device of electrically connecting a plurality of films, at least having electrodes, and connected with an LCD panel, to a circuit board, comprises the steps of:
forming patches of an adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in a circuit board chain which is formed of a series of circuit boards;
breaking the circuit board chain with the adhesive layer attached thereon, into separated pieces of circuit boards;
adhering and fixing the films, at least having electrodes, to the circuit board with an adhesive layer attached thereon, via the adhesive layer; and
electrically connecting the films, at least having electrodes, to the circuit board by joining the electrode terminals on both sides with solder.
In accordance with the thirteen aspect of the invention, a production method for an LCD device of electrically connecting a plurality of films, at least having electrodes, and connected with an LCD panel, to a circuit board, comprises the steps of:
forming patches of the adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in a circuit board chain which is formed of a series of circuit boards;
breaking the circuit board chain with the adhesive layer attached thereon, into separated pieces of circuit boards;
forming an anisotropically conductive adhesive layer on the circuit board chain with the adhesive layer attached thereon;
adhering and fixing the films, at least having electrodes, to the circuit board with the adhesive layer and the anisotropically conductive adhesive layer attached thereon, via the adhesive layer; and
electrically connecting the films, at least having electrodes, to the circuit board by pressing and heating the anisotropically conductive adhesive layer.
In accordance with the fourteenth aspect of the invention, a production method for an LCD device of electrically connecting a plurality of films, at least having electrodes, and connected with an LCD panel, to a circuit board, comprises the steps of:
forming an anisotropically conductive adhesive layer on a circuit board chain which is formed of a series of the circuit boards;
forming patches of an adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in the circuit board chain with the anisotropically conductive adhesive layer attached thereon;
breaking the circuit board chain with the anisotropically conductive layer and the adhesive layer attached thereon, into separated pieces of circuit boards;
adhering and fixing the films, at least having electrodes, to the circuit board with the adhesive layer and the anisotropically conductive adhesive layer attached thereon, via the adhesive layer; and
electrically connecting the films, at least having electrodes, to the circuit board by pressing and heating the anisotropically conductive adhesive layer.
The effects of the invention will be described hereinbelow.
In accordance with an adhesive lamination of the invention, the patches of adhesive layer which correspond to predetermined positions of plural circuit boards are provided so that the adhesive layer can be applied across the plural circuit boards. Thus, it becomes possible to perform multiple production of circuit boards with an adhesive layer, therefore it is possible to produce the circuit boards with an adhesive layer at low cost.
Further, an adhesive lamination of the invention is composed of an elongated, rectangular first separation sheet, a second separation sheet and an elongated, rectangular adhesive layer between the first separation sheet and second separation sheet. The first separation sheet is formed with a plurality of patches of the adhesive layer so that the length of each patch of the adhesive layer is arranged approximately parallel to the short side of the first separation sheet. This arrangement facilitates easy attachment of the adhesive layer onto the circuit board chain and easy separation of the first separation sheet which is adhered to adhesive layer.
In an adhesive lamination of the invention, since the adhering strength between the first separation sheet and the adhesive layer is greater than that between the second separation sheet and the adhesive layer, the second separation sheet can first be removed from the adhesive lamination and then the remaining lamination is pressed with the adhesive layer facedown against the circuit board, thereafter the first separation sheet can be easily removed from the adhesive layer.
In an adhesive lamination of the invention, since a plurality of the first separation sheets are formed on the second separation sheet and the layout of the first separation sheets is repeated or arranged facing each other, it is possible to form many patches of adhesive layer on one adhesive lamination.
In an adhesive lamination of the invention, a plurality of the first separation sheets are formed on the second separation sheet and are shaped in a comb-like form so that a pair of the first separation sheets are laid out mated to one another. Thus, it is possible to reduce the waste of space and increase the number of the first separation sheets for each second separation sheet compared to cases where other shapes are used.
In an adhesive lamination of the invention, since the patches of the adhesive layer formed on the first separation sheet are arranged at intervals corresponding to that of the circuit boards arranged in the circuit board chain which is formed of a series of circuit boards, this feature facilitates easy application of the adhesives layer to the circuit board chain and easy removal of the first separation sheet from the adhesive layer.
In an adhesive lamination of the invention, since the adhesive layer is formed so that each film, at least having electrodes, corresponds to one patch of the adhesive layer, it is possible to keep an uniform distanced between the electrode terminals of the film, at least having electrode, and the corresponding electrode terminals of the circuit board. Thus, it is possible to easily perform the operation for electrical connection by soldering and/or with an anisotropically conductive adhesive as well as to prevent the occurrence of electrical connection defects.
In an adhesive lamination of the invention, since the length of the patch of the adhesive layer is approximately equal to the length of the electrode terminal portion formed on the film, at least having electrodes, stress loads which arise at the electrical contact points between the electrode terminals of the film, at least having electrodes, and the electrode terminals of the circuit board when the portion is tensioned, become substantially even for each contact point between the electrode terminals. Consequently, it is possible to prevent the occurrence of electrical connection defects such as disconnection due to stress loads etc. during the manufacture of the LCD devices.
The production method for a circuit board of the invention is the one for producing the circuit board having an adhesive layer and includes the steps of forming patches of the adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in a circuit board chain which is formed of a series of the circuit boards; and breaking the circuit board chain with the adhesive layer attached thereon, into separated pieces of circuit boards. Therefore, it is possible to improve the efficiency of the operation of forming an adhesive layer onto the circuit boards and thus reduce the cost for the manufacture. For example, when the circuit boards are of a narrow width, since it is possible to take many circuit boards from one circuit board chain, the number of circuit boards in the circuit board chain becomes greater than that of patches of the adhesive layer formed on one circuit board. Therefore, this method is very effective for improvement of the work efficiency compared to the case where the adhesive layer is formed after the circuit board chain was made into separated pieces.
In accordance with an LCD device of the invention, a plurality of films, at least having electrodes, and connected with an LCD panel is adhered and fixed to a circuit board with an adhesive layer, and the electrode terminals of the film, at least having electrodes, are electrically connected to the electrode terminals of the circuit board. In such an LCD device, a number of patches of the adhesive layer are formed corresponding to predetermined positions across a series of circuit boards. Therefore, it is possible to improve the efficiency of the operation of forming an adhesive layer onto the circuit boards and thus reduce the cost for the manufacture. Further, it is easily possible to reduce the width of the frame of the display window of the LCD device and improve the reliability of the electrical connection.
A production method for an LCD device of the invention is of electrically connecting a plurality of films, at least having electrodes, and connected with an LCD panel, to a circuit board, and includes the steps of forming patches of an adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in a circuit board chain which is formed of a series of circuit boards; breaking the circuit board chain with the adhesive layer attached thereon, into separated pieces of circuit boards; adhering and fixing the films, at least having electrodes, to the circuit board with an adhesive layer via the adhesive layer; and electrically connecting the films, at least having electrodes, to the circuit board by joining at the electrode terminals on both sides with solder. Therefore, it is easily possible to reduce the width of the frame of the display window of the LCD device and improve the reliability of the electrical connection.
Another production method for an LCD device of the invention is the one for electrically connecting a plurality of films, at least having electrodes, and connected with an LCD panel, to a circuit board, and includes the steps of forming patches of the adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in a circuit board chain which is formed of a series of circuit boards; breaking the circuit board chain with the adhesive layer attached thereon, into separated pieces of circuit boards; forming an anisotropically conductive adhesive layer on the circuit board chain with the adhesive layer attached thereon; adhering and fixing the films, at least having electrodes, to the circuit board with the adhesive layer and the anisotropically conductive adhesive layer attached thereon via the adhesive layer; and electrically connecting the films, at least having electrodes, to the circuit board by pressing and heating the anisotropically conductive adhesive layer. Therefore, it is easily possible to reduce the width of the frame of the display window of the LCD device and improve the reliability of the electrical connection.
A further production method for an LCD device of the invention is the one for electrically connecting a plurality of films, at least having electrodes, and connected with an LCD panel, with a circuit board, and includes the steps of forming an anisotropically conductive adhesive layer on a circuit board chain which is formed of a series of the circuit boards; forming patches of an adhesive layer which correspond to predetermined positions across a plurality of circuit boards arranged in the circuit board chain with the anisotropically conductive adhesive layer attached thereon; breaking the circuit board chain with the anisotropically conductive layer and the adhesive layer attached thereon, into separated pieces of circuit boards; adhering and fixing the films, at least having electrodes, to the circuit board with the adhesive layer and the anisotropically conductive adhesive layer attached thereon, via the adhesive layer; and electrically connecting the films, at least having electrodes, to the circuit board by pressing and heating the anisotropically conductive adhesive layer. In this way, it becomes possible to effectively form an anisotropically conductive adhesive layer and an adhesive layer. Also, it is easily possible to reduce the width of the frame of the display window of the LCD device and improve the reliability of the electrical connection.